Catalyst recovery



Dec. 22, 1953 M. M. cARDwELL ET AL 2,663,676

CATALYST RECOVERY 2 Sheets-Sheet 1 Filed March 16, 1951 dommmdaod Nw. wl. H Tm. v lv 02@ .mjvvumlmlm W |v N M |v NQ mo 2u3h Om, m |v A mw 3521211" ::zzurni )M )Qrn wby l 0N Q .v1 Nn ma z ww o ml @T .m Qmmu mm EL :.....H.. .dokmzmmd (Johum n. l 3 GN Nw k .I1

'JD-VerlbQrS Dec. 22, 1953 M. M. cARDwl-:LL ET AL CATALYST RECOVERY 2 Sheets-Sheet 2 Filed March 16, 1951 J s mim l lv Nw .m MJUYUM Q53 W mJUXunwd Iv mm m kunoda -IL |v d m AH. :D (Nw. Al NHHL Ow. H m4au uamd 5 )ddDJm 39 m u MmuOPm -)Da M n dmoQ oz 533016 U .d wvo m@ A dmjrrmwf Om dd3|mw @d mvv 426. mw/dokm g vddjl@ 6.1%'. ne s o wir@ 3; ma@ T n m .l

'bg Obborne Patented Dec. 22, 1953 UNITED sTATss PATENT oFFlcE CATALYST RECOVERY Milton M. Cardwell and-Otha C. Roddey, Baton Rouge, La., and Charles W. Tyson, Summit, N. J., assignors to Standard Oil Development Company, a corporation of Delaware Application March 16, 1951, Serial No. 216,049

9 Claims. 'i

This invention pertains to the catalytic conversion of hydrocarbons and particularly to an improved process for the recovery of catalyst particles entrained with vaporous reaction products from a hydrocarbon conversion reactor operating in accordance with the uidized solids technique.

This invention will be described hereinbelow as applied to a fluid hydroforming operation. It Will be understood, however, that it is equally applicable to fluid catalytic cracking or other hydrocarbon conversion operations employing the fluidized solids technique.

Hydroforming is a Well known and Widely used process for treating hydrocarbon fractions boiling within the motor fuel or naphtha range to upgrade the same or increase the aromaticity and improve the antiknock characteristics of said hydrocarbon fractions. By hydroiorming is ordinarily meant an operation conducted at elevated temperatures and pressures in the presence of solid catalyst particles and hydrogen whereby the hydrocarbon fraction is increased in aromaticity and in which operation there is no net consumption of hydrogen. Hydroforming operations are usually carried out in the presence of hydrogen or hydrogen-rich recycle gas at temperatures of 750-1150 F. in the pressure range of about 50-3000 lbs. per sq. inch and in contact with such catalysts as molybdenum ox ide, chromium oxide, or, in general, oxides or suliides of metals of groups IV, V, VI, VII and VIII of the periodic system of elements alone or generally supported on a base or spacing agent such as alumina gel, precipitated alumina or zinc aluminate spinel. A good hydroforming catalyst is one containing about 10 Wt. per cent molybdenum oxide upon an aluminum oxide base prepared by heat treating a hydrated aluminumoxide or upon a zinc aluminate spinel.

It has also been proposed to reform naphtha or gasoline fractions by subjecting them to the action of certain platinumor palladium-containing catalysts at temperatures of 500 to about 950 F. and at pressures of from about atmospheric to about 1000 lbs. per sq. inch at hourly liquid space velocities of from about 0.1 to about 5, in the presence of from about 0.5 to about 10 mols of hydrogen per mol of feed. Catalysts suggested for this purpose comprise 0.2 to about 2.0 wt. per cent of platinum or palladium upon commercial alumina or upon a dry cracking catalyst such as silica-alumina, silica-magnesia or the like. Another catalyst of this type is prepared by precipitating alumina from aluminum l 2 chloride, commingling about 0.1 to about 3.0 weight per cent of hydrogen uoride therewith, adding hydrogen sulfide to a chlorplatinic acid solution, commingling the resultant solution with the fluoride-containing alumina, drying and heating the resultant composite.

It has been proposed in application Serial No. 188,236 filed October 3, 1950, to effect the hydroforming of naphtha fractions in a uidized solids reactor system in which naphtha vapors are passed continuously through a dense, fluidized bed of hydroforming catalyst particles in a reaction zone, spent catalyst being withdrawn from the dense bed and passed to a separate regeneration zone where inactivating carbonaceous deposits are removed whereupon the regenerated catalyst is returned to the main reaction vessel. Fluid hydroforming has several fundamental advantages over fixed bed hydroforming such as 1) the operations are continuous, (2) the vessels and equipment can be designed for single rather than dual functions, (3) the reactor temperature is constant and simulates isothermal xed bed operations, and (4) the regeneration or reconditioning of the catalyst may be readily controlled.

In the conduct of hydrocarbon conversion operations wherein hydrocarbon vapors are passed through a dense, iiuidized, liquid-simulating bed of iinely divided catalyst particles, small amounts of catalyst particles become entrained in the vaporous reaction products and even after passage through cyclone separators or the like which remove the major proportion of the entrained catlyst particles, small residual amounts of catalyst remain in the product vapor stream. It is A desirable, if not essential to the economical operation of this process to recover this residual catalyst from the product vapors. It has been proposed to recover this catalyst by quenching or partially condensing the product vapors to separate the residual catalyst as a slurry, concentrating and, if desired, ltering the slurry, reslurrying the recovered catalyst in fresh feed and introducing the slurry of recovered catalyst and fresh feed to the bottom of the reactor bed.

It is the object of this invention to provide a novel method of recovering iinely divided catalyst particles from vaporous hydrocarbon reaction products produced in a conversion system employing the fluidized solids technique.

It is a further object of this invention to effect the recovery of nely divided catalyst vparticles from vaporous hydrocarbon reactioy While minimizing the reintroduction;

tering the same, reslurrying the recovered natalyst in liquid product and introducingJ the resultant slurry into the upper partzoethe reactor. In this way not only is the catalyst recoveredzbut polymer and other polycyclic compounds' that are adsorbed upon the catalyst particles are stripped from'the catalyst in the disperse phase at the top of the reactor, a zone of relativel'f'v high hydrogen partialpressure and immediately passed uni altered out of the conversionreactor in adlnixture with vaporous reaction'products'. When catalyst withthe said polymers adsorbed thereon is introduced witlrfresh feed into the base of the re- 1 actor, stripping is not soireadily'accomplished because of higher hydrocarbon-'and lower hydrogen partial pressure at the bottom'of the catalyst bed andpassageo the catalyst withsaid. polymers up through the bedsubjectsthe saidpolymers to conversion conditions forvasuflcient period `to cause excessive o ole. depositionon the catalyst because of thehigh carboniorming properties of the polymers under said conversion conditions.

' Moreover, if the recovered catalystparticles are Qsl'urried with fresh iced, the feed Amust vbe cold and thedilute slurrymust beintroduced into the reactor cold because the vcatalyst c o n1 :a1fn ing feed can not be passed throughapreheatng furnace withoutcoking.

'Reference is made .to the accompanyingdrawine illustrating a. .schematicowplan orone embodiment of this invention.

In .thedrawing the feed. or Chalg11g-stock is introduced through' linej I. to. feed-.Pump Hand 1 thence via line I2 ,to.heat. exchange coils, .13erranged in furnace. I4. YThe feedgorrcharg'ing stock may. be' a virgin ,naphtha,a`.cracked. naphtha, v

Fischer-fTrop'sch naphthaorthelike. .When used for catalytic cracking,`the. f e ed stockwould. be a gas oil or similar .high boilingstock. The. feed I stock, preheated in coils." l3:.to. substantially reac- -tion temperature. is then .conductedthrough Vline f.' I 5' to distribution nozzles arranged at or. just above hdistribution .grid I6 `near the.bottomoff reactor V.vessel I8.

.The reactor' I8.is. chargedwith a. mass ofiinely alumina. Suitable crackingcatalysts ,include acid activated bentonite clays, and synthetic composite jnesia and the like. T he catalyst particlesare, for

the'most part between 200,'and'v400vfmesh ein size or about to 200 microns in'diameterwith a' major proportion between rv yandl) microns.

i A stream of hot hydrogen-containing gas containing freshly regenerated or activated catalyst particles is introduced through line I9 into the bottom of the reactor I8 below the grid member I. The grid member serves to distribute the catalyst and gas uniformlyover the full crosssectional area o the reactor. j In starting up the process for the rst time, hydrogen-containing gas may be supplied from an extraneous source.

The process, hoyever, normally evolves hydrogen Y.fand accordingly the hydrogen-containing gas will normally be recycled process gas.

'The'naphtha vapors supplied through line I5 andthe hydrogen-containing gas are passed as a .mixture upthrough the reaction zone at a supercial Velocity of about 0.2 to 0.9 it. per second at Y.reactor..conditions depending upon the pressure.

For example, the velocity should be below 0.6 ft. per second in the pressure range of 20G-250 lbs. per sq. inch gauge. The velocity should be sutilcient to maintainl a dense turbulent, liquidsimulating bed 2c ofsolids and gas having a level 2 l with a dilute phase suspension ofgas and solids 22 thereabove. Lower linear'gas'velocities are used for higher pressures to obtain a dense; fluidized bed. If desired, the reactor I3 may beprovided with horizontally arranged perforated bafiles spaced vertically therein or vertically arranged and spaced baffle membersto improve contacting between hydrocarbon vapors and catalyst.

A vertical internal conduit 23 is provided inthe reactor [8, for the withdrawal of 'catalyst' directly from the dense beol 2). v' The upper end ofv the conduit 23 extends above the lbed level 2i and has an orice or vport 24 at one or more points along its length to permit flow of catalyst'frorn lthe dense bed 26 into the conduit'23. Inasmuehas the catalyst and hydrocarbohsare introduced at the lower end of reactor I8 and product vapors concurrent low of hydrocarbon vapors and catalyst in reactor I S. .The orifice or port 24'may lbe located near the top of bedl 20 toobtain maximum concurrent flow of catalyst and oil vapors up through the. bed 2i). However, theorifice should be suilciently below. thelevel 2l to take. Careof vany normal fluctuations in the.' level12|. More than oneoriiice or port 24 rnay be provided atfdifferent levels in conduit 23 and each port. may .be provided withvalves to control thellow of 'catalyst into conduit 23 and thereby control the .depthof the dense bed 20.

, Steam or an .inert gas such as nitrogenfluegas or the like or mixture thereof is suppliedto conlduit 23 through line 25 near. thebaseofconduitZS conduit23` should be equal to or .higher ,than the supercialvelocity of the vapors. andgases pass- ,.ing upwardly through the reactor I8.

' Thev strippinggasand stripped out constituents are dischargedfrom the top of conduit. into .the dilute phase 22 and are combined with the reaction product vapors leaving thedense bed '20 and the mixture is passed through one or more cyclone separators 26 to remove entrained catalyst particles and then withdrawn throughline v2'! to product recovery equipment described below. 'I he stripping of the lcatalyst particles decreases the amount of combustible material which must be burned off or removed during the regeneration of the catalyst. Ii desired, a separate stripping vessel may be used for the stripping step with the stripping gas and strippedout constituents leaving the stripper being conducted to the reactor outlet line 21 or being separately treated to recover hydrocarbons therefrom.

Stripped catalyst particles are discharged into conduit 28 at the bottom of reactor vessel forming a standpipe for developing the fluistatic pressure necessary to overcome the pressure drop through the regeneration system. If necessary, some additional gas may be added at one or more spaced points in conduit 28. Howevengcatalyst flowing from the base of conduit 23 into conduit 28 will ordinarily carry entrained or trapped gas with it in an amount sufcient to maintain it in a free flowing fluid condition throughout its passage through conduit 28 and iiow control valve 29. Moreover, since the process is carried out under elevated pressures of 100 lbs. per sq. inch or higher which is much higher than the pressure drop through the regeneration system, the amount of pressure build up in the standpipe is relatively small compared to the pressure in the process and consequently there is less compression of the gas entering the top of standpipe 28. In addition by keeping the rate of downflow of solids'in the standpipe relatively high as by making the diameter of the standpipe 2B relatively small as compared to the diameter of the conduit 23, the tendency of the catalyst stream to adeaerate will be reduced if not eliminated.

Catalyst is discharged from the base of standpipe 28 into conduit 36 wherein the catalyst is picked up by a stream of air or other carrier gas supplied through line 3l and compressor 32 and conveyed to regenerator 33. It may be desirable to split the supply of air to the regenerator using only a part of the air necessary for regeneration Afor conveying the catalyst to the regenerator and introducing the remainder of the air at spaced points in the regenerator. While the line 30 for conveying spent catalyst from the reactor to the regenerator is shown discharging into the bottom of the regenerator 33, it may be advantageous to introduce the spent catalyst at the top of the regenerator and eirect regeneration in stages countercurrent to the regeneration gas.

` The velocity of the gas passing `upwardly through the regenerator is controlled to maintain a lower dense, highly turbulent fluidized bed 34 of catalyst particles and gas having a denite level 35, and a dilute or disperse catalyst phase 36 in the upper part of the regenerator. To accomplish this the superficial velocity of the gas passing through the regenerator 33 may range between 0.3 and 1.5 feet per second, depending upon the pressure, for example, at about 1.0 feet per second at a regeneration pressure of about `20D-250 lbs. per sq. inch. A conduit 31 for the withdrawal of regenerated catalyst extends from the middle or upper portion of dense bed 34 downwardly through distribution plate or grid 38 and is connected at its base to transfer line i9. A control valve 39 is desirably provided in the conduit 31 which serves as a standpipe for developing suiicient iluistatic pressure to take care of the pressure drop of the catalyst passing through the reactor vessel. If desired, one or more aeration taps can be provided to keep the regenerated catalyst in standppe 31 in a uid conditionat all times. In order to control the temperature in regenerator 33 it may be desirable to provide coils 40, through which water or other heat exchange fluid may be circulated. The coils are preferably so arranged to have a certain area in contact withthe dense bed 34 at all times with a smaller area extending upwardly into the dilute phase 3E so that the heat exchange capacity of the coils llo may be varied simply by changing the level 35 of the dense uidized bed. The gaseous products from the regeneration are taken overhead, passed through cyclone separators 4| to remove the bulk of the entrained catalyst particles which are returned to the dense bed 34 by the dip pipe attached to the cyclones whereupon the gases are discharged through flue d2 or, if desired, 'processed to recover heat or energy therefrom and/or utilized as stripping gas in the process. A pressure control valve i3 may be used in order to maintain the desired pressure on the regeneration zone.

The freshly regenerated catalyst particles discharged from standpipe 31 into conduit I9 are picked up by a stream of hydrogen-containing gas, preferably recycle process gas. Under the conditions obtaining during regeneration the catalytic metal oxide frequently may undergo a chemical change which affects its catalytic activity. When the freshlyy regenerated catalyst is contacted with the hydrogen-containing recycle gas substantially at regenerator temperature a somewhat exothermic reaction may result during which the catalyst may be restored to its selective form. lt is advisable to control this reaction to avoid permanent deactivation of the catalyst as would occur if, for example, the temperature level reached is too high. Generally, contact of the regenerated catalyst with hydrogen-containing gas at temperatures of not more than about l200 F. for from about 1 to l0 seconds should suiice to render the catalyst suitable for reintroduction into the reactor.

Returning now to the reactor I8, the reaction products as stated above are taken overhead through cyclone separator or separators 2t or the like which removes most but not all of the entrained catalyst particles. The reaction products are then passed through line 21 to product recovery equipment. The reaction products containing small residual amounts of catalyst are passed through a pressure control valve 4d and thence into scrubber 45. In view of the danger of erosion it is desirable to have a second control valve d4 in parallel to facilitate repairs to the valves during operation. The reaction products introduced into scrubber are'contacted with a spray of relatively heavy oil introduced through line 4B. The quenching oil may be a heavy polymer oil formed. in the process or it may be a relatively heavy oil from an extraneous source. rIhe temperature and the amount of quenching oil intro-duced should be suiicient to cool the reaction product vapors below the condensation point of the heavy polymers formed in the process. The droplets of quenching oil and the droplets of heavy polymer formed entrap the small residual amounts of catalyst carried in the product vapors and carry them to the bottom of scrubber 45. The resultant slurry of' catalyst particlesin quenching oil or polymer is-withdrawn from scrubber l5 through line l1 and circulated by slurry i8 through cooler 49 and then through line 4t back into the scrubber. In order to maintain a pumpable slurry, part of the slurry is passed to slurry settler 5c, where catalyst particles are allowed to settle out, clarified oil being withdrawn through line 5| for admiirtiire' L with the "i circulating@ sliry, etce'ss clarified: oil. being #withdrawn from settler l' 5U through .line SZand-"passedfto polymer'fstorage drum 53 or suitable processing equipment.`

The thickenedy `slurry of-.catalystin quenching oilor polymer oil is withdrawn ir'omthe' bottoni of slurry settler 50 through line riand discharged into the thickened slurry recyclepump '55.- In order to remove further amounts of quenching or polymer oil, the'thickened slurry may be n1- tered through-Porostone ltersor `tlieflike and the lter cake thcnvrecycled tothe re'aetoras described belovv.v

The reaction products freed of residual catalyst are taken overhead from the scrubber `t through line 5i, passedr throughy condenser" 51 to condense normally liquid products and thence vialine 5B into an oil-water-gasseparator or knock# out drum 59. Water is withdrawn iromthe knock-out drum 59 through line 50= and-passed into collector SI while liquid product is-withdrawn` from the` knock-outudrum through line'82. The main portion of the. liquid product is passed via line 63 to heat exchanger -54 and thence to stabilizer 65 wherein lower boiling products are taken off overhead through line. E6y While stabilized liquid product is taken oli through line ii', cooled and passed to product storage E8'.

Some of the liquid product'withdraivn from the knock-out drum 59 through line 62 is passed via line E9 to product recycle pump 'l' and thence to' slurry' recycle line 11 i' for adrnixture with the residual catalyst particles recovered from' the reaction products. The' product recycle may bev used to thin cut'. the thickened slurry so that' it maybe readily pumped' back' to' theA reactorY or, if' the slurry of catalyst in polymer oil withdrawn from settler is filtered, the product re-` cycle may be used for hackwashing the lter to make a pumpablev slur-ry of catalyst for recycling to the reactor.

In accordance with this invention the slurry of recovered'cat'alyst in liquid product is recycled via line "Hi to thev top of the reactor ahead of the reactor cyclones. The slurry'is preferably introduced Vatl or near thel dense4 bed disperse phase interface since in this'region the hydrogen partial pressure is at a maximum. due' to the hydrogen produced in the Yconversion'. High h ydrogen partial pressure facilitates thestripping of'polyme'r and heavy products adsorbed by the catalyst particles. Itis especially desirable to' strip off th'ese heavy polymers at the top ofthe reactor in order to avoid" subjecting these materials, which have pronounced carbon 'forming properties; to conversion conditions which would convert said polymers to coke or other carbonaceous deposit to the detriment of the activity of the catalyst. The product stream used for reducing the' thickened slurry or slurrying, the lter cake is especially suitablek for'this purpose' because `of the fact that. having oncepassed through the reactor these products are'r relatively stable and, therefore, are' not adverselyfaiecte'd by"'rec'ycling" to' the' top of'thereactor.' Fresh feed isnctsuitable for this purpose since i'tw'ould pass; essentially "unaltered'out of the reactor. It may be'desirable in some cases to vornittlieslurry settler completely, in which'ca's'e all cf'the heavy productAV would be -returnedftothe Vtopof' the reactor or toY thicken the slurry onlyE to'a limited extentzso that itwill'remainz'pu'mpableso that it may be A-returnedfto -the #reactor top 'without dilution.l

Returning again to therseparatorfor knock-out drum 59, recycle gas iswithdrawn .through line 12. compressed in`4 recycle gas compressioni and passed through heat esch'angefcoiis Min #fuif-1 nace I4 where they are heated to'temperatuies sufficiently high to convey a substantialfpart 'if not all the heat required vfor the reaction; The preheated recycle gas vWithdrawn Afrom coils- `I4 picksup the regenerated catalyst particles'discharged from standpipe 31 and conveys the saine through conduit IB into the reactor lI8.- The excess ygas over that needed for recycle andto maintain pressure is 'withdrawn from separator 59 throughline 'l5 and combined, ifdesired, with the gas removed from the stabilizer 65 and recovered or used as fuel.

While the `foregoing description hasndisclosd in detail the use of the presentinventi'on ida fluid hydroforming process, it Willbe understood that it may be used-as well in other hydrocarbon' conversion operations employing the fiuidi'zed solids technique. In catalytic cr'acl'r-ing, for 'efx' ample, gas recycle would be eliminted and ytle preheated feed stock would be miedwitfi hot regenerated catalyst from standpipe' 31' ao passed through line I8 into Ythe bttori'f' tl reactor. Partial condensation of' the product will permit recovery. of residual --catalys'ftas slurry in heavy cycle stck. This cycle k similar to the heavypolymerffrom the hyd di forming operation forms much earbonuderftle conditions in the reactor bed'and accordingly' thickening the slurry or sacchetto remove-"nie buik of the heavy 'cycle steek gaswinning. the slurry or backwashing the l't' with lighter cracked product to form-A a p rpableslui" of recovered catalyst and introducing this' slur yat the top of the reactor permitsrap'd strippi goiy adsorbed cycle stock from the 'catalfyfstl with u@ appreciable cracking thereof to cok'e as :would occur if the slurry Was charged to the bottoniof the reactor.

The foregoing speciilcation'c'ontainsa limited nurnherof embodiments of the present invention: It willbe understood, however', that 'numerous variations are possiblewithout departingfroiii the scope of the following claims'.

What' is claimed is 1. In a process for the conversion@ hydro: carbons` in contact with finely divided'catlyst particles in accordance vWith thegiidzedfslis" technique wherein hydrocarbon 'feed stock s" tacted with a dense', luidied bed ofcata'lys't particles in the-lower portion of the:` conversion zone, the improvement which comprises u'fi'tlidrawing a stream o f vaporous reaction products containingresidual' ai'n'ount's of entrai'ried c'at alyst particles fromV the top of the conversion zone, partially condensing `the product vapors to' separate the residual catalyst' asia 'slurry 'in heavy product and recycling" the recovered residual cati alystdirectly into the disperse phase in the'upper portion of the conversion Zo'n'e. Y

2. In aprocess for the conversione-f "hydr carbons in contact with nely divided catalyst particles in accordance" with the fluidlzed's'olids technique wherein hydrocarbon feed s 'tock" is contacted with a denseVfluidizedjbw of catalyst particles in the*v lower portion'of"the'ic'onvrsio zone, the improvement which comprises'with' drawing 'a' stream of vaporous reacticnprodts" v containing small residualamounts oi' eri'train'ed catalyst particles' from the top of the conversion zene, .partially condensing .the product. vapcrst' separate the-residualcatalyst' as' a slurrylri' heavy. product, separating a part-ofthe heav-'y product f from lsaid slur-ryand recyclngthe recovered residual catalyst directly into the disperse phase in the upper portion of the conversion zone.

3. In a process for the conversion of hydrocarbons in contact with nely divided catalyst particles in accordance with the fluidized solids technique wherein hydrocarbon feed stock is contacted with a dense, iiuidized bed of catalyst particles in the lower portion of the conversion zone, the improvement which comprises Withdrawing a stream of vaporous reaction products containing residual amounts of entrained catalyst particles from the top of the conversion zone, partially condensing the product vapors to separate the residual catalyst as a slurry in heavy product, separating a Dart of the heavy product from said slurry, adding lighter liquid product in sufficient amount to form a pumpable slurryand recycling the pumpable slurry of recovered residual catalyst directly into the disperse phase in the upper portion of the conversion zone.

4. In a process for hydroforming hydrocarbon fractions boiling within the motor fuel range in contact with finely divided hydroforming catalyst particles in accordance with the fiuidized solids technique wherein hydrocarbon feed stock is contacted with a dense, fluidized bed of hydroforming catalyst particles in the lower portion of the hydroforming reaction zone, the improvement which comprises withdrawing a stream of hydroformate vapors containing small residual amounts of entrained hydroforming catalyst particles from the top of the hydroforming reaction zone, partially condensing the hydroformate vapors to separate the residual -catalyst particles as a slurry in heavy polymer and recycling the recovered residual hydroforming catalyst directly into the disperse phase in the upper portion of the hydroforming reaction zone.

5. In a process for hydroforming hydrocarbon fractions boiling within the motor fuel range in contact with finely divided hydroforming cata` lyst particles in accordance with the uidized solids technique wherein hydrocarbon feed stock is contacted with a dense, iiuidized bed of hydroforming catalyst particles in the lower portion of the hydroforming reaction zone, the improvement which comprises withdrawing a stream of hydroformate vapors containing small residual amounts of entrained hydroforming catalyst particles from the top of the hydroforming reaction zone, partially condensing the hydroformate vapors to separate the residual catalyst particles as a slurry in heavy polymer, separating a part of the heavy polymer from said slurry and recycling the recovered residual hydroforming catalyst directly into the disperse phase in the upper portion of the hydroforming reaction zone.

l6. In a process for hydroforming hydrocarbon fractions boiling within the motor fuel range in contact with finely divided hydroforming catalyst particles in accordance with the fluidized solids technique wherein hydrocarbon feed stock is contacted with a dense, fluidized bed of hydroforming catalyst particles in the lower portion of the hydroforming reaction zone, the improvement which comprises withdrawing a stream of hydroformate vapors containing residual amounts of entrained hydroforming catalyst particles from the top of the hydroforming reaction zone, partially condensing the hydroformate vapors to separate the residual catalyst particles as slurry in heavy polymer, separating a substantial part of the heavy polymer from said slurry,

10 yadding lighter liquid hydroformate in suilicient amount to form a p-umpable slurry of recovered residual hydroforming catalyst and recycling this slurry directly into the disperse phase in the upper portion of the hydroforming reaction zone. 7. In a process for hydroforming hydrocarbon fractions boiling within the motor fuel range in contact with finely divided hydroforming catalyst particles in accordance with the iluidized solids technique wherein hydrocarbon feed stock is contacted with a dense, fluidized bed of hydroforming catalyst particles in the lower portion of the hydroforming reaction zone, the improvement which comprises withdrawing a stream of hydroformate vapors containing small residual amounts of entrained hydroforming catalyst particles from the top of the hydroforming reaction zone, partially condensing the hydroformate vapors to separate the residual catalyst particles as a slurry in heavy polymer, separating a substantial part of the heavy lpolymer from said slurry, filtering the thickened slurry to remove further amounts of heavy polymer forming a pumpable slurry by adding hydroformate to the filter cake and recycling the resultant slurry directly into the disperse phase in the upper portion of the hydroforming reaction zone.

8. In a process for cracking hydrocarbon oils in contact with finely divided cracking catalyst particles in accordance with the iiuidized solids technique wherein hydrocarbon feed stock is con tacted with a dense, iluidized bed of cracking catalyst particles in the lower portion of the cracking reaction zone, the improvement which comprises withdrawing a stream of cracked hy-l drocarbon vapors containing small, residual amounts of entrained catalyst particles from the top of the cracking reaction zone, partially condensing the cracked vapors to separate the residual catalyst particles as a slurry in heavy cycle oil, separating a substantial part of the heavy cycle oil from said slurry and recycling the recovered residual cracking catalyst particles directly into the disperse phase in the upper portion of the cracking reaction zone.

9. In a process for cracking hydrocarbon oils in contact with finely divided cracking catalyst particles in accordance with the fluidized solids technique wherein hydrocarbon feed stock is contacted with a dense, fiuidized bed of cracking catalyst particles in the lower portion of the cracking reaction zone, the improvement which comprises withdrawing a stream of cracked hydrocarbon vapors containing residual amounts of entrained catalyst particles from the top of the cracking reaction zone, partially condensing the cracked vapors to separate the residual catalyst particles as a slurry in heavy cycle oil, separating a substantial part of the heavy cycle oil from said slurry, adding lighter liquid cracked product in suilicient amount to form a pumpable slurry of recovered residual cracking catalyst particles and recycling this slurry directly into the disperse phase in the upper portion of the cracking reaction zone.

MILTON M. CARDWELL. OTHA C. RODDEY. CHARLES W. TYSON.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,429,161 Hudson Oct. 14, 1947 2,541,635 Boyer Feb. 13, 1951 2,549,518 Perry Apr. 17, 1951 

1. IN A PROCESS FOR THE CONVERSION OF HYDROCARBONS IN CONTACT WITH FINELY DIVIDED CATALYST PARTICLES IN ACCORDANCE WITH THE FLUIDIZED SOLIDS TECHNIQUES WHEREIN HYDROCARBON FEED STOCK IS CONTACTED WITH A DENSE, FLUIDIZED BED OF CATALYST PARTICLES IN THE LOWER PORTION OF THE CONVERSION ZONE, THE IMPROVEMENT WHICH COMPRISES WITHDRAWING A STREAM OF VAPOROUS REACTION PRODUCTS CONTAINING RESIDUAL AMOUNTS OF ENTRAINED CATALYST PARTICLES FROM THE TOP OF THE CONVERSION ZONE, PARITALLY CONDENSING THE PRODUCT VAPORS TO SEPARATE THE RESIDUAL CATALYST AS A SLURRY IN HEAVY PRODUCT AND RECYCLING THE RECOVERED RESIDUAL CATALYST DIRECTLY INTO THE DISPERSE PHASE IN THE UPPER PORTION OF THE CONVERSION ZONE. 